I’m colour deficient. (I’m explicitly *not* colour-blind.) No, I’m not sensitive about the matter, that’s more in jest. The origins of the distinction date back to Grade 1 though: I mention to friends in class:
“hey, I’m colour blind!”
they ask: “what colour’s this?”
“what colour’s that?”
“what about and that?”
“you’re not colour blind!”
Ha! Well, we were seven years old. What do you expect?
In any case, here’s my ‘lil invention, that I sadly haven’t implemented for myself: carry around a red and green filter. Or even a blue one as well, if you need it.
Allow me to sketch an over-simplified way of how we see colour…
Our eyes are sensitive to “three colours”. But that isn’t actually true. They are sensitive to three ranges of colour. Suppose you see some yellow light, with wavelength 580 nanometer (abbreviated nm, that’s a millionth of a millimetre). This lies between the wavelength for red light and green light (620–750 nm and 495–570 nm respectively). Your eye does not get stimulated for “yellow”, it gets stimulated for red to the one side, and green to the other, which we then interpret as “yellow”. For this reason, and this reason alone, we can simulate yellow light with a computer or TV screen by combining red and green light. (Yes, red and green light together looks like yellow.)
The image above (source: Wikipedia) shows the wavelength sensitivities of our eye, notice the heavy overlap between red and green. Along the horizontal axis is the colour (according to the wavelength of the light), and the vertical is how each is perceived by the eye. It suggests that light that is right in the middle of our green-sensitivity still looks more than 80% red to our “red receptors”. Our brains or neural networks interpret something that stimulates “100% green” and “80% red” as green.
Now to colour-blind people, it is often this distinction between red and green that they find hard to make. My idea is to externalise the filtering between red and green. A red filter (a piece of plastic that lets through red light, aka red plastic) will let through red light unhindered, while suppressing “not red” wavelengths, while a green piece of plastic lets through green light unhindered, suppressing the rest.
Again these filters will overlap, but the better you can get them to differentiate, the sharper you can make their graphs as mentioned above, the bigger their effect will be on the red and green light they let through. Under the pair of filters, red light should look dimmer on the green side, and green light should look dimmer on the red side.
Maybe something like this would help us poor colour-deficient people from telling apart different resistor values — in electronics the amount of resistance on a resistor is encoded by a couple of coloured lines. Maybe if I had these filters, I would have opted for hardware instead of software!
Naah, kidding, I got by. My deficiency isn’t too bad. It presents itself in a couple of interesting places, such as sometimes having to look twice to distinguish orange and yellow on a Rubik’s cube… while it sounds like most people find the orange to be closer to the red than to the yellow (?!) — what do you think?
Canon PowerShot woes!
The biggest evil though, the biggest handicap this is for me right now, is Canon. Yes, Canon. Canon is being evil towards us poor colour deficient people. I can not for the life of me determine whether my Canon PowerShot camera’s batteries have finished charging or not… the battery charge indicator is a mix between red/green or (or yellow/green for all I know?) representing charging/charged, and even after plugging out the battery and plugging it back in, to get the light to switch from charged back to charging, to have something to compare to, doesn’t help me! Sometimes, yes, I can determine the answer with suitable certainty, but these days I simply plug in the batteries for “long enough”. Which means it is impossible for me to charge three batteries in “as short a time as possible”.
I see a vague 21, or some other shapes if I search for them, but I can’t even point out where the 74 is suppose to be.
- Simplified human cone response curves, based on Dicklyon’s PNG version, itself based on data from Stockman, MacLeod & Johnson (1993) Journal of the Optical Society of America A, 10, 2491-2521d (log E human cone response, via http://www.cvrl.org/database/text/cones/smj2.htm)
- Ishihara Plate 9 – public domain – You MUST NOT use this image in diagnostics.